Stockholm Vatten och Avfall (SVOA) participates together with eleven partner organisations in Sweden, Finland, Estonia and Latvia in the BalticPFASResolve project, an Interreg Central Baltic Programme 2021–2027 project co-funded by the European Union. SVOA is the coordinator of one of the project work packages. Within this work package, an interactive digital model is being developed to clearly illustrate which water flows and activities contribute PFAS loads to the sewer system and reaches wastewater treatment plants. The model is intended to provide an overview of where the largest loads originate and serve as a decision-support tool to enable targeted measures where they have the greatest effect. In this way, emissions from wastewater treatment plants can be reduced, thereby contributing to the protection of the Baltic Sea. To enable this, a consultant will be procured to support the development of a digital mass balance model for PFAS upstream of wastewater treatment plants. The model will be used by project partners to analyse PFAS flows from different sources within catchments and sewer networks.